According to prosecutors, Kercher was killed during "an erotic group [sex] game that span completely out of control."

Knox was initially convicted and sentenced to 26 years in prison. Sollecito was sentenced to 25 years.

But in 2011 an Italian appeals court overturned their convictions and harshly criticized the prosecution's handling of evidence. Knox, now 25, had just recently resumed her studies at Washington University in her hometown of Seattle.

The court accused the judges in the appeals case of underestimating the evidence against Knox and Sollecito, claiming that the acquittal contained "shortcomings, contradictions, and inconsistencies."

The New York City sighting Tuesday sparked rumors that Knox and Sollecito had gotten back together.

"You only have to look at him to see he still holds a huge torch for Amanda. He clearly finds her captivating," one onlooker told the Mirror. "When they hugged she closed her eyes as he gave her a tender kiss on her cheek. At one point he put his arm around her to help warm her up. They never once stopped chatting."

Knox sat down with ABC's Diane Sawyer in April for her first on-camera interview.

"I want the truth to come out," Knox said. "I'd like to be reconsidered as a person."